SPDIF to AES

You are good going Spdif to AES, but may not be ok AES to spdif. It depends on what receiver they are using. Svart posted a link in his converter thread to a white paper on how to build the voltage converter network.

I usually only recommend this in 6ft or less,
but the Nuetrik Digital transformer [or similar] is preferable if possible

Looks like it's between this and the Neutriks that adamjbrass mentioned. It'll be about the same price between the two. I can't (or shouldn't) go straight wire AES to SPDIF. There's an impedance mismatch, 110 to 75ohm.

Casey from Bricasti recommeds:

"These would be my choice for proper SPDIF to AES EBU conversion:
Neutrik NADITBNC-F
Neutrik NADITBNC-M

This is a Male/Female pair of passive impedance converters for AES to SPDIF on BNC. You would then also need a pair of Female RCA Phono to Male BNC converters, such as these:
Pearstone RCA Female to BNC Male Adapter

Then a pair of standard SPDIF cables and a pair of standard AES EBU cables."

I haven't found a cheaper off the shelf solution. Given that the Hosa and Neutriks are the same price, I may go with the Neutriks with RCA/BNC adapters.

SPDIF and AES are identical in data protocol but slightly different in physical transmission characteristics such as voltage level and impedance..  HOWEVER, there is an AES version called AES3ID that is actually single ended 75R specification, and it's pretty much identical to SPDIF in all ways except that the "professional" bit is set in the data stream..

But I digress.


For SPDIF->AES, you just hook the RCA center to XLR pin 2, ground the other pins on the XLR.

For AES->SPDIF, there are two ways to look at it..


You can either hook the RCA center to XLR pin 2 and hook RCA shield to XLR pin 1 and leave pin 3 floating.. This is possible since MOST modern digital receiver ICs are actually sold as BOTH AES and SPDIF capable and the only difference is whether a bit is set during configuration to tell the encoder/decoder whether it's SPDIF or AES. Most of the time this will work without any level conversion, but as mentioned, this works best if the cable is fairly short because the impedance mismatch might allow reflections on longer cables.

OR

you can find the AES->SPDIF pad schematics online.  It's a PI pad that pads the level a little and does impedance conversion.


cbcmusicblog.files.wordpress.com/2010/11/aes_to_spdif_adapter1.jpg

That's killer, svart! I would have given this a try, for sure.

Biggest problem with SPDIF is the RCA jack, for short runs an adaptor cable will work 98% of the time.
The HOSA is pretty good, the Neutriks are the gold standard.